Latitudinal variation in the ionospheric parameters: a Soviet-Indian experiment by simultaneous launchings

Abstract

Coordinated ion-neutral composition and electron density measurements have been carried out over Thumba (India) and Volgograd (U.S.S.R.), near sunrise. One of the launchings from Thumba revealed the turbopause to be around 110 km. Large fluctuations in ion and electron densities were also registered in the altitude region 105-125 km, along with oscillatory structures in the neutral composition, indicating that unusual conditions prevailed during this measurement. Contrary to expectations, 'time synchronous' launchings from Thumba and Volgograd revealed nearly identical distributions of neutral species. The turbopause altitudes during these flights were also the same within the limits of experimental uncertainty. These measurements confirm that the role of the turbopause and temperature are mutually independent in governing the distribution of neutral composition in the thermosphere.